The present invention relates generally to batteries, fuel cells and electrochemical cells, and more particularly to separators used in such devices. The invention is particularly applicable to lithium-ion polymer batteries and will be described with respect thereto. It will be appreciated, however, that the present invention finds advantageous applications in other devices, such as those indicated above.
Most batteries include a component referred to as a xe2x80x9cseparatorxe2x80x9d that is adapted to separate, and prevent direct contact between, an anode section and a cathode section. In addition to maintaining physical separation of the anode section and the cathode section, a separator is designed to perform several other functions such as forming an ionic pathway between the anode section and cathode section, electronic insulation, mechanical support and as a layer binding the anode section and cathode section. Each of these requirements often dictates the need for different and sometimes opposite material properties. For example, a material having high tensile strength may have poor flexing properties, or a material having a high porosity may have poor adhesive properties. Thus, the design and manufacture of a separator for use in a battery requires a balancing of a number of material properties such as mechanical strength, adhesion, porosity and processability.
The present invention provides a multi-layered separator component for use in an electromechanical device, where the multi-layered separator has at least two layers formed of different separator materials and wherein each layer has different physical properties than the other.
In accordance with a preferred embodiment of the present invention, there is provided a separator for a lithium-ion polymer battery that is comprised of a plurality of separator layers that are laminated together. The plurality of separator layers includes a first layer formed of a first separator material and a second layer formed of a second separator material, wherein the second layer is structurally and compositionally different from the first layer.
In accordance with another aspect of the present invention, there is provided a Li-ion and/or Li-ion polymer cell that is comprised of a cathode section, an anode section and a multi-layered separator disposed between the anode section and the cathode section. The multi-layered separator includes a first layer formed of a first separator material and a second layer formed of a second separator material, wherein the first layer has different physical properties than the second layer.
In accordance with another aspect of the present invention, there is provided a method of forming a Li-ion or Li-ion polymer battery having a multi-layered separator, comprising the steps of:
a) forming an anode section and a cathode section, the anode section having an anode layer adhered to an anode current collector layer and the cathode section having a cathode layer applied to a cathode current collector;
b) laminating a first separator layer formed of a first separator material to the anode layer of the anode section and laminating a second separator layer formed of a second separator material to the cathode layer of the cathode section, wherein the first separator layer is compositionally and structurally different than the second separator layer;
c) laminating the anode section to the cathode section wherein the first separator layer and the second separator layer are disposed between the anode section and the cathode section.
It is an object of the present invention to provide a separator component for an electromechanical device.
It is another object of the present invention to provide a separator component as described above, wherein the separator component is comprised of multiple layers, wherein each layer is formed of a different separator material having different physical and/or chemical properties.
Another object of the present invention is to provide a Li-ion and/or Li-ion polymer cell having a multi-layered separator as described above.
A still further object of the present invention is to provide a method of forming a multi-layered separator as part of a Li-ion and/or Li-ion polymer cell.
These and other objects will become apparent from the following description of a preferred embodiment taken together with the accompanying drawings.